Rosacea is a chronic inflammatory skin disorder of unknown cause. It is most common in Caucasians with fair complexions, and usually starts in middle age or later.
When taken by mouth, isotretinoin (13-cis-retinoic acid), a synthetic derivative of vitamin A, raises the level of vitamin A in the skin and is often effective. However, because of its potential toxicity, it needs to be taken under medical supervision. There is also early evidence that topical application of a form of vitamin A called tretinoin (vitamin A acid; retinoic acid) may be as effective as oral isotretinoin. Your dermatologist can prescribe both of these medicines.
Sometimes rosacea appears to be due to a deficiency of the B vitamins caused, most often, by malabsorption because of insufficient stomach acid. When this is the case, the combination of hydrochloric acid and vitamin B complex seems to cause the condition to clear, although no scientific (double-blind) studies have been done to confirm this.
If you are curious about this possibility, find a physician who will test you for hydrochloric acid levels and who, if indeed you are deficient, will help you to find the right supplemental dose of betaine or glutamic hydrochloride. (These supplements, while available without a prescription, can cause stomach irritation and even bleeding if the dosage is too high, so I’d advise taking them only under a physician’s supervision.)